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<H3>dihedral_style fourier command 
</H3>
<H3>dihedral_style fourier/omp command 
</H3>
<P><B>Syntax:</B>
</P>
<PRE>dihedral_style fourier 
</PRE>
<P><B>Examples:</B>
</P>
<PRE>dihedral_style fourier
dihedral_coeff 3 -0.846200 3 0.0 7.578800 1 0 0.138000 2 -180.0 
</PRE>
<P><B>Description:</B>
</P>
<P>The <I>fourier</I> dihedral style uses the potential:
</P>
<CENTER><IMG SRC = "Eqs/dihedral_fourier.jpg">
</CENTER>
<P>The following coefficients must be defined for each dihedral type via the
<A HREF = "dihedral_coeff.html">dihedral_coeff</A> command as in the example above, or in
the data file or restart files read by the <A HREF = "read_data.html">read_data</A>
or <A HREF = "read_restart.html">read_restart</A> commands:
</P>
<UL><LI>m (integer >=1)
<LI>K1 (energy)
<LI>n1 (integer >= 0)
<LI>d1 (degrees)
<LI>....
<LI>Km (energy)
<LI>nm (integer >= 0)
<LI>dm (degrees) 
</UL>
<HR>

<P>Styles with a <I>cuda</I>, <I>gpu</I>, <I>omp</I>, or <I>opt</I> suffix are functionally
the same as the corresponding style without the suffix.  They have
been optimized to run faster, depending on your available hardware, as
discussed in <A HREF = "Section_accelerate.html">Section_accelerate</A> of the
manual.  The accelerated styles take the same arguments and should
produce the same results, except for round-off and precision issues.
</P>
<P>These accelerated styles are part of the USER-CUDA, GPU, USER-OMP and OPT
packages, respectively.  They are only enabled if LAMMPS was built with
those packages.  See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A>
section for more info.
</P>
<P>You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
switch</A> when you invoke LAMMPS, or you can
use the <A HREF = "suffix.html">suffix</A> command in your input script.
</P>
<P>See <A HREF = "Section_accelerate.html">Section_accelerate</A> of the manual for
more instructions on how to use the accelerated styles effectively.
</P>
<HR>

<P><B>Restrictions:</B>
</P>
<P>This angle style can only be used if LAMMPS was built with the
USER_MISC package.  See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A> 
section for more info on packages.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "dihedral_coeff.html">dihedral_coeff</A>
</P>
<P><B>Default:</B> none
</P>
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